Group Number: _________Member Names: ___________________ _______________________ECE4112 Internetwork SecurityWireless securityGroup Number: _________Member Names: ___________________ _______________________Date Assigned: Date Due: Last Edited: Lab authored by: Anders Davoust, Nils KjellinPlease read the entire lab and any extra materials carefully before starting. Be sure to start early enough sothat you will have time to complete the lab. Answer ALL questions in the Answer Sheet and be sure youturn in ALL materials listed in the Turn-in Checklist on or before the Date Due.GoalThe goal of this lab is for the students to get an understanding of the potential weakness in WPAand WPA2 run in PSK-mode. After completing the lab they should have been introduced to somemethods to avoid the weaknesses.Summary: First we will setup a wireless connection between an access point and a Windows XP machine.We will then boot a machine with BackTrack 2 linux live-cd operating system, and run the toolsto obtain the key. The key will then be used to access the wireless network. The same procedurewill be repeated for WPA2. Equipment: The access point we are going to use is a Linksys WRT54GL wireless router. We will use aWindows XP machine with a wireless network card and a Linux machine with another wirelessnetwork card. The network card on the linux machine has to have an Atheros-based chipset. Weare also going to use a CD with BackTrack 2 to boot from. Backtrack can be found at thefollowing address:http://www.remote-exploit.org/backtrack_download.htmlBackground/Theory: WPA - Wi-Fi Protected Access WPA comes in two flavors. One for home users with a pre shared key as master key and one forenterprises that requires an authentication server to provide the master key. It was designed as a1predecessor to WEP, which had several security flaws. The major improvement is the use ofTKIP (Temporal Key Integrity Protocol), which regularly changes the keys dynamically. WPAalso uses larger IVs (initialization vectors) than WEP, which prevents key recovery attacks thatwere possible with WEP. [4] To initiate a WPA-PSK session a 4-way handshake is required. This 4-way handshake makes itpossible to confirm that the client knows about the PSK (Pre Shared Key) and derive a new PTK(Pairwise Transient Key), a temporary key generated for each session. The PSK is generatedfrom a passphrase that both the access point and the client must know.Reference: http://www.wi-fiplanet.com/tutorials/article.php/10724_3667586_1The access point initiates the handshake by generating a random number ANonce that is sent tothe supplicant. The supplicant now has enough information to generate the PTK. The PTK isgenerated from the PSK, ANonce, SNonce, and the MAC addresses of the involved parts. Thesupplicant then sends a hashed version of the PTK, called MIC, along with the SNonce to the AP.This message is to prove to the AP that he has derived the PTK from the PSK. The AP can now generate the PTK, since it now also has the SNonce. The AP verifies that it isthe correct PTK by hashing it and comparing it to the MIC. If they match it knows that thesupplicant knows the PSK needed to generate the PTK. The third message contains the GTK(Group Transient Key) decrypted with the PTK and anotherMIC. The GTK is used to decrypt multicast and broadcast traffic. The MIC is calculated with a2part of the PTK. When the supplicant receives this message, the MIC is checked to ensure thatthe authenticator knows the PMK and has correctly calculated the PTK [3].The last message acknowledges completion of the whole handshake and indicates that thesupplicant will now install the key and start encryption [3].The problem with this algorithm is that all the information used for calculating the PTK istransmitted in plain text, which give us the opportunity to perform an offline dictionary attack. Ifwe capture the handshake sequence we can start calculating the MIC by guessing the passwordand perform the same operations as done in the handshake. If we get the same MIC we havefound the password.A problem with this is that this is a very slow process. We need to perform 4096 hashes for eachpassword attempt[5]. A computer can only test 50 to 300 possible keys per second depending onthe computer CPU [1]. It can take hours, if not days, to crunch through a large dictionary.[1] Tospeed up this process we can take advantage of pre computed lookup tables. Instead ofcalculating the hash for each password we can look up the hash corresponding to a certainpassword in pre computed tables. This process is much faster. For example, a 2006 Shmoocondemo[7] showed coWPAtty testing 18,000 passphrases per second. [6] When hashing thepassphrase the SSID is seeded into the hash. This means that the passphrase of 'password' will behashed differently on a network with the SSID of 'linksys' than it will on a network of 'default'.[5] This means the lookup tables will be different if the SSID is different. Here is torrent for a file containing lookup tables for the 1000 most commons SSIDs using a 172000 word dictionary: http://torrents.lostboxen.net/cowf-wpa-psk-hash-tables-with-cowpatty-4.0_2006-10-19EAP - Extensible Authentication Protocol802.1x is a standard for port-based Network Access Control, not limited to wireless networks.WPA implements parts of the 802.1x and WPA2 implements it fully. 802.1x uses EAP(Extensible Authentication Protocol) for authentication. EAP is only a framework and supportsaround 40 different mechanisms of authentication. Among them are, EAP-TLS, EAP-TTLS/MSCHAPv2, PEAPv0/EAP-MSCHAPv2, PEAPv1/EAP-GTC, EAP-SIM and EAP-LEAP. These are all included in the WPA/WPA2 Enterprise certification program. TLS requirescertificates at both ends, while PEAP only require a certificate at the server side. [4]Traditional 802.1X/RADIUS solutions require a dedicated RADIUS server and a rather complexsetup. One way of avoiding this is to use the software developed here at Georgia Tech, tinyPEAP.tinyPEAP allows you to have all of the benefits of 802.1X and PEAP security without the hassleof having a full blow RADIUS server on hand [8]. Lab Scenario: 1.1. Setting up the wireless network3- Connect a network cable between your computer and the wireless AP. - Start your Windows XP machine and connect to the AP using the web-interface.